Rotating screw stoppers have long been used to control the flow through a tap or faucet. The screw has an exterior end mounted to a handle. The screw, commonly in the form of a stem or arbor, is threadably engaged to a housing and mounting a mobile valve seal or washer at the interior end.
As the screw valve is tightened, the washer is compressed against a valve seat. However, the washer by being rotated as it compressed against the valve seat until the stem was fully tightened unduly wore both the washer and the valve seat. While the washer could be replaced, the valve seat could not. Furthermore, the stem rose out of the housing as the valve was opened which many users deemed undesirable. Non-rising stem valves have been developed that use shearing action of a valve seal. However, compressive valves are often still desirable due to the better sealing seating available through compressive action. More non-rising stem valves have been developed that continue to use compressive action of the seal against a fixed valve seat.
A non-rising stem stopper essentially compresses a shell, intended to be affixed securely to the body of a faucet device. A mobile fitting is mounted in an axially movable manner and in a nonrotatable manner inside the shell of the stopper and bearing a valve seal. An operating stem is mounted for rotation and fixed in an axial direction in the shell o the stopper. The stem has one end inside the shell, linked by a screw threading to the mobile fitting, and an outer end that protrudes form the shell of the stopper and constructed to mount an operating handle. Rotation of the handle causes axial shifting of the mobile fitting and the valve seal which, cooperating in a timely fashion with a valve seat placed between the intake passage and the outlet passage of the body of a faucet valve brings about the desired adjustment of the water flow.
Traditionally, the valve seal, supported by the mobile fitting, was made up of a packing disc consisting of elastomeric material. The mount of the inlet passage is formed in the body of a faucet, itself as a valve seat that cooperates with the packing disc to adjust the flow. An example of this traditional arrangement is provided in document DE-U-94 18 554.
With this arrangement, a sealing washer made of elastomeric material was subject to deterioration. After deterioration, the washer can be easily removed by dismantling the shell of the stopper form the body of the set of cocks, taps and valves. Furthermore, the repair was inexpensive. A simple washer with a central hole was attached via a bolt.
However, the valve seat that cooperates with this washer is also subjected to deterioration. Due to the valve seat being a part of the body of a cock, tap or valve, it can be restored only by working on it with a suitable manual milling machine. Such a repair is not an easy operation nor are the results always satisfactory and the repair cannot be repeated more than several times.
An attempt was therefore undertaken to make this valve seat on a separate member that is screwed into the body of the faucet and that can be extracted so that it may be repaired or replaced. Such a modification results in an excessive increase in the cost of the faucet.
Furthermore, the operations involved in disassembly and reassembling the applied valve seat are not easy and require special tools.
An attempt was made to remedy this inconvenience, for example, as disclosed in document EP-B-O 606 419. In this disclosure, the valve seal is a rigid element forming a part of the mobile fitting of the stopper. A special packing made of elastomeric material installed in the shell itself fits tightly against the mount of the intake passage presented by the body of a faucet and which, will cooperate with the rigid vale seal presented by the mobile fitting of the stopper. The body of the faucet is thus protected against any deterioration; but the special necessary packing must have a complex configuration and is therefore expensive. The shell of the stopper also requires relatively expensive processing to manufacture a seat intended to receive such a packing.
According to International Patent Application WO 93/24774, the use of a packing with a complex shape was avoided by installing a first ferrule that forms a ring-shaped shoulder in the end of the body of the stopper with the stop bolt. A second ferrule is installed inside the first one that received a static packing intended to provide a seal against the mouth of the inlet passage of the faucet body. The interior end of the second ferrule holds an elastomeric retaining sealing member by a spring toward the shoulder of the first ferrule. The mobile fitting of the stopper moves axially onto the sealing element for shutting off flows and rises away from the sealing element to an open position. A disadvantage of this arrangement is that two ferrules must be used. Besides the added costs and complexity of two ferrules, the presence of two ferrules adds thickness inside the shell of the stopper. This increased thickness limits the diameter of the elastomeric sealing member and the passage therethrough which in turn restricts the maximum flow volume of the stopper under maximum opening conditions.
Furthermore, in the known stopper constructions, the pressure of the water works on the mobile fitting over a large cross section, giving rise to a relatively powerful force that must be overcome by working the stopper. Furthermore, as the elastomeric sealing member wears out or is crushed, the mobile fitting axially advance an increased distance position to provide the seal in the closed position in turn which entails inconveniences and interferes with the service life of the packing. In addition, the known valve stopper has static packings placed between the shell of the stopper which can yield only to a very limited degree. The distance between the region in which the valve stopper shell is screwed onto the faucet body and the surface of the body against which said static packing must establish a successful seal becomes critical. In some cases, manufacturing here requires compliance with excessively restricted tolerances, which again causes higher costs and gives rise to the possibility of inconveniences due to the heat expansion of the parts.
What is needed is a valve stopper with a non-rising stem so as to be sealed against the body of the faucet with the use of a simply shaped packing and without any need for expensive work on the shell of the stopper. It is further needed to have a packing and that can be easily accessed and replaced when it has worn out or is broken. What is also desired is to increase maximum flow rates of a valve stopper for a given outer dimension and to decrease the total force due to the water pressure against the mobile fitting to reduce the force needed to operate the valve stem. It is also desired to incorporate a device to reduce the noise level connected with any severely restricted flow of water.
It is further desirable to construct such a stopper that may have increased manufacturing tolerances as to the distance between the region in which the stopper is installed in the faucet body and the surface of the body where the seal must be established with the packing seal.